Braking system



AUS' 1l, 1953 J. n. RUSSELL 2,648,413

BRAKING SYSTEM Filed OCT.. 15, 1949 2 Sheets-Sheet l n a 30 n /8A 3/ /2 /5 f4 il- Ivg* JNVENTOR. JOHN D. Russia, BY

/MM Kfm/M J. D. RUSSELL BRAKING SYSTEM Aug. 11, 1953 2 Sheets-Sheet 2 Filed Oct. l5, 1949 7a ca/L .366

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TTOR/VEK Patented Aug. 1'1, 195,3

UNITEDV STATES PATENT OFFICE- BRAKING sYs'rEM reim D'.- Russeu, Iles Angeles, Calif.

Application ,campen 1-5, 1949; seriarNo. 121,546 2 claims'. (c1. raz-3i This invention relates to vehicle brakingsysA tems and more particularly to automaticcontrol means for such braking systems. Y Y

The conventional motor vehicle, asv for exam,- ple an automobile, has a-braking systeml incl-uding brake shoes or other braking means associated with at least two, but more generally four of its wheels, a brake pedal located in the 'automobile cab, hydraulic, mechanical or other means operable responsive to depression of the brake pedal to apply the separate braking means at each wheeL. and an emergency brakeoperable from the cab to apply the braking `means ontwo or more of the wheels independently ofthe brake pedal.

I have now developed a brake control system which operates automaticallyv to set the brakes,v The which may be of any conventionalV type. control system of the invention may be used independently or in conjunction with the iconventional brake operating means and brake pedal.

In one form, the invention provides (l) an auto-`r matie emergency brakecontrol which applies'the' inamotor vehicle having an-acceleratorwpedal f to control the speed of the vehicle motor, and

braking means associated with the-vehicle wheels,

the combination comprising-a sourcefof electrical i energy, means operable by movement of theac-r celerator pedal to initiate energy outputifrom thel source to apply the braking -means-.- Inra pre' ferred embodiment, the energyl output of zthe source is not only initiated by movement of the accelerator pedal butv is ialsowvaried responsive to the magnitude of pedal movementyand. the means vfor applying the brakes responsive-tothe output of the source varies the brakin-gforcey ap-f plied in proportionto the variation in the energy output of the source.

A feature of thebrake control Asystem of thef invention is its complete -independence'vfromex--VU isting brake control means Vand' the Vcomplete"50/01"1-3 e11f11 t0 the bkof pedal lil at l5 and is pivotabsence of interference between'the two.l If the*l operator oi a motor `vehicle-desiresto employ thef conventional brake pedal, additionalfbraking may be achieved 'although the brakes: will-have been applied.automaticallyfbefore-he will-have'beenh V`valve arm-22 forming apart 0f carburetor- 24;

ableto place his foot on the brake pedal. Moreover, the sensitivity of the automatic control system maybe varied by a manually operated control as described above and the same control may be used to cut out the automatic control system completely,` if desired. p

Then-*ultimate aim of the invention is to make possible theelimination of the conventional brakel pedal altogether and make all braking automatic with movement of the accelerator pedal. This is in line with the present trend of automatic transmissions which have successfully eliminated the` clutch pedal. By elimination of the brake pedal, the operator is left with a single foot pedal performing both the accelerating and braking functions.

Theinvention will' be more clearly understoodY with reference to the following detailed descriptionrrtaken in conjunction with the accompanying drawings whereing Y* Fig. 1 is ablockdiagram of a complete system inaccordance with the invention; y

Fig 2 is a diagrammatic sectional elevation of onegrneans -for applying the `brakes through' the application ofV pressure developed responsive to the output of` the energy source; v

Figli 3 isA a diagram of an alternative means of applying the brakes responsive to the output of the,energy source;

Figr 4 is a-diagram of a portion of the system showing a particular type'of energy source and its operation responsive to movement of the acceleratorpedal;

Eig.; 51s a detailed diagrammatic illustrationV of the automatic emergency brake system as forminga part of the complete system'of Fig. 1; and,`

Fig.. e is a diagrammatic iiiustrauon of asimpliedfsystem for initiating output of the energy source responsive to movement of the pedal and the -application ofthis'ioutput to energize the brake system. n

Referringto `Fig. l, there is shown in diagram a conventional accelerator pedal lo, pivottally 1rngyunted at H yto a floor i2, say of an automobile; The pedal can be rotated about the pivot point I l through an angle approximately dened` by the phantom positions IIIA, lB of the pedal. Atoggle--arrangement l@ is pivotally mounted at allyV mounted at'its opposite end to a stationary knee 2U of thetoggleand connects teV a butterfly The throttle arm I8 is extended beyond the butterfly arm 22 and through the medium of a rack 28 and pinion 2'I controls a so-called servo-drive unit 28. Both buttery arm 22 and rack 28 are connected to the throttle arm through slots 38, 3l respectively oriented with respect to each other so that during the movement of the accelerator i8 in the range defined by position IUA, the rack and pinion are inoperative and during the movement of the pedal I8 in the range defined by position IDB, the butterfly valve is not affected.

Looking at the pedal It, depression towards the right to the phantom position IDA actuates the butterfly arm 22 without movement of the rack 26. Return of the pedal from the position IA to the illustrated position actuates the butterfly arm in the opposite direction, still without moving the rack 26. Rotation of the pedal I in the opposite direction to the phantom position 18B shifts the rack 2li to the left thereby rotating pinion 2l and return of the pedal to the intermediate position I0 shifts the rack 28 in the opposite direction, the entire rack shifting procedure taking place without change in the buttery valve setting.

A spring 32 loads the toggle I4 against depression of pedal I8 to the position IA and a spring loaded roller 34 engaging against an inclined face ISA of the throttle control arm I8 urges pedal I0 once it is in the intermediate position to the position IDB. Thus, considering the position of the pedal as illustrated in solid lines as an intermediate position, movement thereof between this position and the position IBA controls the vehicle acceleration whereas movement between this position and the position IBB controls the vehicle braking independent of acceleration.

The servo-drive unit 28 comprises a source of electrical energy preferably variable responsive to the angular rotation of pinion 2'I. An electrical servo follower 36 is connected to the output of the servo-drive unit 28 and comprises electrically operated means for applying the brakes either directly or indirectly. Thus, if the braking system happens to be electrical it may be operated directly responsive to the electrical servo follower 36. However, if the braking system is hydraulic which is normally the case, a pressure servo 38 is connected to the electrical servo follower and is operated thereby to apply the brakes directly as indicated by arrow 39 or to apply pressure to the master -cylinder 48 of the hydraulic braking system which is transmitted through the normal hydraulic line 42 to the brakes.

In a preferred embodiment, the automatic control system includes an electro-mechanical transducer 44 operable responsive to pressure applied thereto from the hydraulic master cylinder 48 to feed back an electrical signal to the servodrive unit 28 by means of a lead 45. This feedback serves to stabilize the automatic control by applying a signal to the drive unit opposite to that developed responsive to rotation of the pinion gear 2I. When the operator of the automobile applies pressure to the master cylinder by depression of the conventional brake pedal, this pressure may be of such magnitude as to develop a feedback signal in the transducer 44 suicient to cancel out the output of the servo-drive unit 28 and hence to cancel the operation of the automatic brake control.

The energy input into the servo-drive unit 28 is determined by a manual control means 48 which may be a simple rheostat or potentiometer oper- 4'.: able by a control knob in the' automobile cali.- The supply of energy through the control 48 to the servo-drive unit is in turn derived from battery 58 of the automobile through a relay 52 operable responsive to the position of the automobile ignition switch 54 and generator 55 in such a fashion that the control system is dead, i. e. there f is no current now from battery 50 through relay 52, manual control 58 and the servo-drive unit 28 when the ignition switch 54 is in the off position or when the ignition switch is on but the motor is not running. Relay 52 is a double coil double pole relay, the two coils 52A, 52B being separately energized through different circuits. When the ignition switch is turned on, before the motor is started there is no current through either coil. When the motor is started generator 55 closes relay 5'I to energize coil 52A. This closes both contacts of relay 52 completing the circuit from battery 50 to the servo-drive unit and also completing the circuit through coil 52B. With coil 52B energized, the ycircuit will remain closed even though the motor stops until ignition switch 54 is turned off.

An automatic emergency brake system represented in the diagram by an emergency brake coil 56 is connected in the circuit between relay 52 and manual control 58 and is operative when there is no current ow between the relay and the manual control, i. e. when the ignition switch is olf and becomes inoperative When the ignition switch is turned on and the motor is started as above described.

The operation of the system of Fig. 1 is as follows: depression of pedal I0 in the direction of -position IDA increases through displacement of butterfly arm 22 the speed of the vehicle motor, at the same time having no effect on the braking control system. Relaxation of the pressure on pedal I0 to allow it to return to the intermediate position decelerates the vehicle still without effect on the braking control system. Further relaxation of the foot pressure on foot pedal I0 allowing the pedal to travel in the direction of position IDB under the urging of spring loaded roller 34 causes the rack 26 to travel toward the left rotating pinion gear 21 clockwise. Assuming that the manual control means 48 is set to energize the servo-drive unit 28 and the circuit is closed through relay 52, rotation of pinion gear 2'I will initiate electrical output from the drive unit 28 and in a preferred embodiment will vary this output responsive to the degree of rotation of the pinion gear.

As mentioned previously, the output of the servo-drive unit may be employed directly to apply the brakes in an electrical braking system. However, most motor vehicles are presently provided with hydraulic brakes and the invention is described primarily with relation to such braking means. The output of the servo-drive unit is fed into the electrical servo follower which may comprise a motor, a solenoid or an electro magnet as more fully explained hereinafter. These various expedients may be used directly on the hydraulic fluid to apply the brakes. In one embodiment, the electrical servo follower operates the pressure servo 38 which by one means or another hereinafter set forth develops a hydraulic pressure in the hydraulic master cylinder to applyr the brakes. The pressure developed in the hydraulic master cylinder is transmitted through the existing uid lines 42 to the brakes and a portion thereof is bled from these lines in the electro-mechanical transducer 44. The transaceaeie ducer 44 feeds an electrical signal of a magnitude proportional to the pressure applied thereto back to the servo-drive unit to oppose the output signal of the drive unit. The emergency brake system 58 is described in greater detail with respect to Figs. 5 and 6.

In Fig. 2, there is shown one type of pressure servo operable responsive to the output of the electrical servo follower, the electrical servo follower 38 being in this case a motor (not shown) operative to oscillate shaft 58 which in turn opcrates the pressure servo 38. The pressure servo illustrated in Fig. 2 comprises a cylinder 60 slidably mounted on two stationary pistons 62, 53 sealing the opposite ends of the cylinder 60. A source of pressure (not shown) as for example the oil system of the vehicle is connected by a manifold 6.43 and ports 65, 66 to the cylinder. A pressure exhaust manifold 68 is connected to the cylinder through ports 69, providing means for bleeding pressure from the cylinder. In case the oil system of the vehicle is tapped as the pressure source, the manifold 68 may exhaust the pressure directly into the crankcase (not shown). A piston` 12 is slidably mounted within cylinder 58 between the stationary pistons 62, 83 and is connected by piston rod 14 to the existing piston (not shown) in the hydraulic master cylinder lll (see Fig. 1). The piston 12 is provided with ports 15, 11 opening into the cylinder at opposite ends of the piston and alignable with ports 65, 66 respectively in the cylinder wall. In operation, energy output from the servo-drive unit applied to the electrical servo follower, in this case a motor, causes the motor to shift the shaft 58 towards the right (as Viewed in Fig. 2) displacing the cylinder to align the port 85 in the cylinder with the port 16 in the piston 12. Pressure, say oil pressure, is thus introduced to the cylinder on the left hand side of the piston 12 at the saine time displacing port 18 so as to bleed pressure from the inside of the cylinder on the right of piston 12. Pressure introduced on the left of the piston 12 causes the piston to travel towards the right, applying through piston rod 14, a pressure on the hydraulic system. Piston 12 thus follows cylinder 68, the displacement of which is proportional to the rotation of pinion 21. When the electrical servo motor is reversed responsive to reversal of the pinion 21,

the operation of the pressure servo 38 is likewise reversed, pressure being introduced on the right hand side of piston 12 and exhausted from the left hand side of piston 12. 'Ihis retracts the piston in the hydraulic master cylinder through the medium of piston rod 14 and releases the brakes.

In a simplified system employing the pressure servo follower of Fig. 2, the shaft 53 may be connected through suitable mechanical linkage to the throttle arm i8. In such a system all electrical components are eliminated but at the same time sensitivity adjustment is rendered more difficult.

Another type of pressure servo is illustrated diagrammatically in Fig. 3. In this figure, the servo-drive unit 38 is of the type hereinafter described with reference to Fig. 4 and the output of the drive unit is applied to electrical servo follower' 3B (as shown in Fig. l) which in this particular embodiment comprises coils 36A, StB. The pressure servo 33 (see Fig. l for the relationship of the pressure servo to the servo-driver unit and electrical servo follower) comprises a self contained hydraulic circuit consisting of a hydraulic fluid line connected to th input and output of a pump 82 and a bypass 84 short circuiting the duid line 80 through a .control valve 85. The coils 36A, 36B, are placed around the line 80 on opposite sides of a pressure chamber 85 opening into the line 80. The pressure chamber 88 contains a diaphragm 88, a shaft 89 connected at one end to the diaphragm and extending through a wall of the chamber 86 and a helical spring 9B mounted around the shaft 89 and loading the shaft downwardly as viewed in the drawing.

The hydraulic system including line 8D, pump 82 and bypass 84 is lled with a magnetic fluid i. e. a fluid oil having suspended therein a quantity of iron particles. A fluid of this type is characterized by a sudden increase in viscosity under the influence of and proportional to the strength of an applied magnetic field.

In the apparatus of Fig. 3, such a magnetic eld may be induced in the fluid `by either of coils 36A or 36B. If the servo-drive 28 is operated to energize the coil 36B the viscosity of' the magnetic fluid adjacent the coil 36B increases markedly and a preselected portion of the pres-- sure developed. by pump 82 is transmitted into This pressure distorts:

the pressure chamber 86. diaphragm 88 thereby displacing the shaft 89.. By connecting the shaft 89 to the regular hydraulic master cylinder piston, or to an auxiliary master cylinder piston the brakes will be applied in the automobile responsive to distortion of the diaphragm 88. The amount of pressure applied to the pressure chamber 86 responsive to energization of coil 86B will be a function of the capacity of pump 82 and the setting of the bypass control valve 85 as well as the strength of the magnetic eld. Any desired proportion of the pump output pressure may be short circuited to the pump inlet through the bypass 84. When the servo-drive unit vis oppositely actuated, coil 36B will be deenergized and coil 36A will be energized. Under these circumstances, the viscosity block in the hydraulic line 80 will be upstream from the pressure chamber 86 and the substantial flow of hydraulic fluid will be through bypass 84. Under these circumstances, there will be no pressure in chamber 86 and the spring 90 will retract shaft 89, thus relieving the brakes. An accumulator 92 is connected in the hydraulic line 8l] intermediate the pump and rst coil 36A and operates on the principle of a surge tank to smooth out operation of the system. The degree of braking may be adjusted to a desired value by proper proportioning of energization of coils 36A and 36B through the electrical servo-drive unit.

In the embodiment of Fig. 3, the particular servo-drive unit required includes one source of energy initiated responsive to movement of the throttle pedal in the braking range and another source of energy initiated responsive to motion of the throttle pedal in the accelerating range. With reference to Fig. 3, the energy output of the servo drive unit 28 initiated by and responsive to the motion of the throttle pedal in. the braking range energizes coil 36B and deenergizes coil 36A in proportion to throttle movement upward whereas the output of the servodrive unit initiated by and responsive to movement of the throttle pedal in the accelerating range energizes coil 38A and deenergizes coil 36B. Such a system is shown in somewhat greater detail in the diagram of Fig. 4.

In Fig. 4, throttle pedal I0 is again connected through a toggle I4 to a throttle control arm I8 Ioperative to alter the position of butterfly valve larm 22. Butterily arm 22 is connected to the throttle arm |8 through a slit 30 which permits motion of the throttle arm |8 in the braking range of pedal movement without effecting the 'throttle valve. A pivot arm 96 is connected at 'one end to the outer end of throttle arm I8 and is pivotally mounted intermediate its ends to a stationary support 98. In the particular Kembodiment shown in Fig. 4, the pivot arm 96 is connected by shafts |00, on opposite sides of the pivot point 96 to a pair of carbon stacks |02, 1I03 respectively. The characteristic of carbon stacks of this type is a change in resistance inversely proportional to the compressive force applied thereto. By connecting a substantially constant source of electrical energy as for example the automobile battery, through stacks |02, |03 to the coils 36B, 36A respectively (see Fig. 3), the energy impressed on these coils is responsive to the compressive force applied to the stacks by movement of the lever arm 96. Thus when the throttle |0 is depressed in the accelerating range, the lever arm 96 pivots counterclockwise compressing stack |03 and relieving the pressure on stack |02. This decreases the resistance of stack |03 and increases the resistance of stack |02 to the point where coil 36A is energized and coil 36B is deenergized. Under these conditions, referring to Fig. 3, there is no pressure developed in the chamber 86 and no braking action takes place. When the pedal I0 is released beyond the intermediate position, being urged in the opposite direction by the spring loaded roller 34, the lever arm 96 rotates in clockwise direction with the result that coil 36B is energized and coil 36A is deenergized in proportion to the angular displacement of arm 96. Under these conditions pressure is applied to the chamber 86 actuating the brakes in the manner above described.

lThe carbon stacks |02, |03 are representative of any variable resistance device or variable energy output device as a rheostat, potentiometer or the like operable by mechanical movement responsive to rotation of the lever arm 96.

Returning to Fig. 3, the system there shown may be modied by elimination of valve 85 and shifting of coil 36A to the bypass 84. As thus changed the system is controlled by in-phase energization and deenergization of coils 36A and 36B. As a consequence a single current output from the servoedrive unit will suffice. Referring to Fig. 4 this means that carbon stack |03 may be omitted with both coils being connected to the stack |02.

The details of the automatic emergency brake .system shown only as the emergency brake coil 56 in Fig. l are illustrated diagrammatically in lFig. 5. The emergency brake comprises a ratchet |06 pivotally mounted at |01 to a stationary sup- ;port |08. The emergency brake lever ||0 is pivotally mounted at |01 and is rotatable independently of the ratchet |06. As is conventional practice, the lever ||0 is provided with a dog |I2 engageable in the ratchet and connected through a latch arm ||3 to a lever ||4 projecting downwardly along the arm I0. Rotation of lever ||4 towards the arm ||0 releases dog I|2 from the ratchet |06. A brake actuating cable ||6 is connected to the upper end of arm ||0 above pivot |01 so that clockwise rotation of arm ||0 applies the emergency brakes through the cable I I6 and counterclockwse rotation releases the brakes. A housing |20 is divided into two compartments |20A and |20B by a transverse diaphragm |22. A rod |24 is connected at one end to the diaphragm |22 and is carried through a wall of the housing |20 and pivotally aixed at its opposite end to the ratchet |06. In the particular embodiment shown, diaphragm |22 is spring loaded by a helical spring |26 which urges the diaphragm towards the left thereby pivoting ratchet |06 and brake handle I I0 clockwise and applying the emergency brakes. An electrical valve |28 is connected through a conduit |29 to chamber |20A and through a conduit |30 to a vacuum source (not shown). Conveniently, the vacuum source is supplied by the vehicle motor. An air inlet line |32 is also connected to the valve |28. When the emergency brake coil 56 (in valve |30) is energized by turning on the ignition switch 54 and starting the motor (see Fig. 1) the valve |28 connects conduits |30 and |29 to partially evacuate the chamber |20A drawing the diaphragm |22 and conjunctively rod |24 to the right (as viewed in Fig. 5). The ratchet |06 and emergency brake handle ||0 are thereby rotated counterclockwise to release the brakes through cable ||6. When the ignition switch is turned off coil 56 is deenergized, valve |28 moves to connect conduits |28 and |29 allowing air to relieve the vacuum in chamber |20A and permitting spring |26 to force the diaphragm towards the left thereby applying the brakes. A breather port |24 opens into chamoer |20B to permit intake and exhaust of air as the diaphragm |22 moves. The same arrangement can be used with a pressure source by connesting conduit |29 to chamber |20B, providing the exhaust port |24 in chamber |20A.

A simpliiied version of the invention is illustrated in Fig. 6 wherein automatic control is provided to the extent of on-off control of the brakes without the refinement of variable braking or variable sensitivity. The apparatus of Fig. 6 is associated with a conventional brake pedal |40 pivotally mounted at |42 to a stationary support |43 and operating a piston |44 in the hydraulic braking system through suitable and conventional linkage. Depression of the brake pedal |40 (towards the right in Fig. 6) forces piston |44 to the left to apply the brakes. A conventional accelerator pedal |46 is pivotally mounted at |41 to a stationary support |48 and controls the displacement of a throttle arm |49 pivotally mounted to the under side of the pedal. A housing |52 is provided with a diaphragm |54 connected by means of a rod |55 to the brake pedal |40. The diaphragm |54 is spring loaded with a spring |56 to urge the diaphragm outwardly with respect to the housing |52 i. e. against depression of brake pedal |40. The housing |52 is connected through a conduit |58 to an electrical valve |59 which is connected through a conduit |60 to a vacuum source and to atmosphere through a conduit |62. The housing |52 is also connected directly to atmosphere through a conduit |64 having a valve |66 disposed therein. The valve |59 is normally positioned to connect conduits |58 and |62 thereby venting the housing |52 to atmosphere.

The valve |59 is actuated by a coil |68 connected through a relay |69 to the automobile battery |10. The relay |69 is energized by closing ignition switch |12 to complete the circuit between the battery and one side of coil |63, The other side of coil |68 is connected through a pair of parallel coupled switches |14, |15 to a stationary contact |16 placed adjacent the throttle arm |49. The throttle arm |49 carries a grounded contact |18. Switch |14 is a manually operable switch conveniently located in the automobile cab by means of which the automatic braking control system may be cut out or not as desired. Switch |15 is a motion control switch which is closed only when the automobile is stopped. The purpose of the switch |15 will be made apparent from the following description of the operation of the system of Fig. 6.

With the switch |14 closed and the ignition switch |12 turned on, the circuit through electrical valve control coil |68 is completed from battery to contact |16. While the automobile is being accelerated by foot pedal |46 contacts |16 and |18 are disengaged so that no current flows through coil |68. In this condition the chamber |52 is connected to atmosphere through valve |59 and conduit |62. When the pressure on the accelerator pedal |56 is released to the point where contacts |16 and |18 engage, current passing through coil |68 actuates valve |59 to connect chamber |52 through conduit |80 to a vacuum source (not shown). Evacuation of chamber |52 draws diaphragm |54 inwardly which, through shaft |55, rotates the brake pedal |40 clockwise to apply the brakes through piston |44.

As described above, the apparatus of Fig. 6 represents a simplified system wherein there is no electrical sensitivity control and the braking forces applied by manipulation of the throttle pedal |46 is substantially xed. Some sensitivity control can be achieved by adjustment of valve |68 on the air vent |84. The braking forces applied being a function of the displacement of diaphragm |54 is thus a function of the degree of vacuum in chamber |52. Assuming a constant source of vacuum, the pressure in chamber |52 may be controlled by adjusting valve |66 to permit a sm-all amount of air low through conduit |64.

If it is desired to deactuate the automatic braking control system the manually operated switch |14 may be opened, in which case, except under circumstances hereinafter explained, no current will flow through coil |68 even upon engagement of contacts |18 and |18. By inclusion of a motion switch in parallel with the manually controlled switch |14, automatic hill holding may be achieved independent of other automatic brake operations. The motion switch |15 is adjusted to close only when the automobile is stopped. Hence, when travelling up or down a hill, if the automobile is stopped by foot depression of pedal |40, the motion switch |15 will close and coil |68 will be energized by engagement of contacts |18, |18 until the throttle is depressed for renewed motion of the car.

A feature of the apparatus of Fig. 6 is that it functions independently of and at the same time in conjunction with the normal foot operated brake, thus, if the driver takes his foot off the throttle pedal, assuming switch |14 to be closed, to apply the brakes, braking action will take place, the extent of which depends upon the degree of vacuum and the setting of valve |68, even during the interval required to move his foot from throttle pedal |46 to brake pedal |40. If greater braking is required, the pedal |40 can be further depressed in the conventional manner.

Many modifications in the apparatus of the invention may occur to those skilled in the art,

10 the invention being directed to an automatic braking control system in which the emergency brake operation is responsive to the ignition switch and motor and regular braking is obtained automatically responsive to manipulation of the accelerator throttle.

I claim:

l. In a motor vehicle having a battery, an accelerator pedal to control the speed of the vehicle motor, braking means associated with the vehicle wheels, and a brake pedal operable by depression to apply the braking means, the combination comprising a housing, a flexible springloaded diaphragm sealed across the housing and forming a chamber therein, a shaft connected at one end to said diaphragm and at the other end to said brake pedal, a source of vacuum, an electrically actuated valve operable to connect said chamber alternately to said source of vacuum and to atmosphere, a grounded electrical contact mounted to move responsive to motion of said accelerator pedal, a stationary electrical contact mounted in the path of motion of said grounded electrical contact, the stationary contact being connected through a manual control switch to one side of said electrically actuated valve, the other side of said electrically actuated valve being connected to said battery through a relay operable responsive to closing the vehicle ignition switch to close the circuit between said battery and said valve.

2. In a motor vehicle having a battery, an accelerator pedal to control the speed of the vehicle motor, braking means associated with the vehicle wheels, and a brake pedal operable by depression to apply the braking means, the combination comprising a housing, a exible springloaded diaphragm sealed across the housing and forming a chamber therein, a shaft connected at one end to said diaphragm and at the other end to said brake pedal, a source of vacuum, an electrically actuated valve operable to connect said chamber alternately to said source of vacuum and to atmosphere, a grounded electrical contact mounted to move responsive to motion of said accelerator pedal, a stationary electrical contact mounted in the path of motion of said grounded electrical contact, the stationary contact being connected through a manual control switch to one side of said electrically actuated valve, the other side of said electrically actuated valve being connected to said battery through a relay operable responsive to closing the vehicle ignition switch to close the circuit between said battery and said valve, and a motion control switch connected in parallel to said manual control switch so that said valve is actuated automatically when the vehicle is stopped independent of the setting of said manual control switch.

JOHN D. RUSSELL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,635,873 Woolson July 12, 1927 1,682,308 (Schaede Aug. 28, 1928 1,857,053 Krotz May 2, 1932 2,082,430 Townsend June 1, 1937 2,266,213 Kattwinkel Dec. 16, 1941 2,308,822 Murphy Jan. 19, 1943 2,334,611 Darling Nov. 16, 1943 2,387,716 Chilton Oct. 30, 1945 2,411,632 Moren Nov. 26, 1946 2,412,228 Oetzel Dec. 10, 1946 

